1. Field of the Invention
This invention relates to asphalt products having enhanced tear strength, and more particularly, to asphalt composites including an adhesion modifier, preferably a polysiloxane treated, glass fiber mats which can meet the current ASTM D-3462 standard for tear strength required of asphalt roofing shingles.
2. Description of the Prior Art
Asphalt is a dark brown or black cementitious material comprised predominantly of bitumins that occur in nature or are obtained as a residue in the refining of petroleum. Asphalt has been used for many years for roofing and road-paving applications to form a water-impermeable barrier between the environment and an underlying surface. However, in its pure state, asphalt is not quite suitable as a water-impermeable barrier since it is brittle in freezing temperatures and fluid in hot temperatures. Accordingly, the prior art has modified the asphalt both in a composition aspect and in combining the asphalt with carriers or reinforcing materials so as to provide asphaltic products with the desirable properties of tear strength, flexibility, stability and the like.
Presently, the ASTM D-3462 standard for tear strength for asphaltic roofing composites or shingles is met by the industry by increasing the weight of the mat and/or asphalt in the shingle, and by modification of urea-formaldehyde binders used therein, both of which methods are costly to the manufacturer.
Accordingly, an object of the present invention is to provide an asphalt roofing composite with glass fiber mats having enhanced tear strength, and particularly asphalt roofing shingles which can be in compliance with ASTM D-3462, without requiring an increase in the weight of the shingle or of modifying conventional binders used therein.